Induction furnace crucible



-July 16, 1968 l R. A. FALK INDUCTION FURNACE CRUCIBLE Filed sept. 21. 196e 5S. ya)

United States Patent O 3,392,970 INDUCTION FURNACE CRUCIBLE Richard A. Falk, 519 Westminster Drive, Waukesha, Wis. 53186 Filed Sept. 21, 1966, Ser. No. 580,950 2 Claims. (Cl. 263-48) ABSTRACT OF THE DISCLOSURE Disclosed herein is a refractory crucible for an induction combustion analyzer which has an inner V-shaped floor formed by generally semicircular faces which slope inwardly and downwardly to intersect at a line which is a diameter of the inner cylindrical wall.

The present invention relates generally to refractory crucibles and more particularly to a crucible for an induction combustion analyzer with an inner oor adapted to facilitate complete and rapid burning of the sample.

According to the present invention, a crucible for a combustion analyzer is provided with a V-shaped inner oor to assist in positioning of a pin sample in the same relative position with respect to a combustion analyzer and to insure contact of accelerator material with the combustion sample.

The crucible #of the present invention is constructed rfor use in a combustion analyzer using an induction heating coil such as that disclosed in Patent No. 2,809,100. In operation of this type of combustion apparatus, a sample taken from a steel melt in the form of a pin is volatilized by induction heating in a stream of oxygen. The combustion gases are drawn off and may be analyzed by any conventional technique as for example by gas chromatographic analysis or by Orsat type volumetric gas analysis apparatus. To facilitate combustion, an accelerator material such as iron, copper, or tin, in the form of chips or fillings is commonly placed in the crucible surrounding the sample.

One of the problems encountered in the use of a cornbustion furnace with -gas analyzer apparatus is that the apparatus has a limited gas volume capacity. If a complete volatilization of the sample is not accomplished prior to reaching the gas capacity of the apparatus, inaccurate data will be obtained. Typical high speed gas analysis apparatus will automatically shut down when a certain volume of gas is received. Other gas analysis equipment is automatically turned olf by a timer after a brief period. Accordingly, it is imperative that complete and rapid volatilization and combustion of the sample occur before the capacity of the analysis apparatus is reached or automatic shutdown takes place. Failure to attain this result necessitates repeated tests with the same steel melt, causing substantial costly delays in the foundry process. Moreover, the rapid volatilization of the sample is desirable to facilitate quick determination of the composition of the steel melts which is an essential in modern foundry practice.

The device of the present invention avoids these problems by insuring contact of the accelerator material with the sample to promote the desired rapid and uniform burning. In addition, the V-shaped il'oor also permits always locating the pin axis in the same position or direction relative to the induction coil in successive tests. Conventional cr-ucibles do not have any structure in the crucible to prevent lateral movement of the sample while the crucible is installed in the combustion chamber. Inasmuch as experience has demonstrated that the induction coil Will heat the sample at dilferent rates depending on the alignment of the pinv axis with respect to the coil, samples ice can be repeatably positioned in the coil in the position that proves to be most effective for rapid combustion using my disclosed structure. Identical positioning of each sample will increase the accuracy of comparative tests on different melts.

Further objects and advantages of the present invention will become apparent from the following disclosure in which: i

FIGURE 1 is a side perspective view of the combustion crucible embodying the present invention with a portion broken away;

FIGURE 2 is a plan view of the crucible shown in FIGURE 1;

FIGURE 3 is a sectional view of the crucible shown in FIGURE 1 taken along line 2 -2; and

FIGURE 4 is a vertical cross-sectional view of the crucible installed for operation in the combustion chamber of gas analysis apparatus.

Referring now to the drawings, FIGURE l shows a crucible constructed of any suitable high temperature resistant refractory material and generally designated 10, having an outer cylindrical wall 12, an inner concentric cylindrical wall 14, an inner floor 16, and a base 18. The crucible 10 has outside dimensions that permit use in conventional combustion analyzers. In the embodiment of the invention disclosed herein, the cylindrical wall has a diameter of approximately 1.125 inches, but may be modified to adapt the crucible for use in any specific combustion chamber. Although the crucible embodying the invention illustrated herein comprises a cylindrical container, any other suitable construction such as sloping walls converging toward the base could be used.

The inner floor 116 is adapted to secure a pin sample against lateral displacement and facilitates identical positioning Iof each sample in the combustion chamber by a groove transverse to the axis of the inner cylindrical wall 14. In the disclosed construction, the -groove is provided by two generally semicircular faces 20 and 22 which slope inwardly and downwardly and intersect at a line which is a diameter of the inner cylindrical wall 14. The faces 22 and 20 are integral with inner wall 14 and provide a V- shaped bottom as shown in FIGURE 3. Some of the advantages of the present invention can be obtained with a U-shaped channel of the approximate dimensions of the pin sample in the crucible floor. However, with the use of a V-shaped inner floor, the accelerator material 29 is funneled or directed toward the sample 24, which is desirable to insure maximum contact of the accelerator material with the pin for rapid burning.

By providing the pin sample 24 with stability from lateral movement while in the crucible 10, the crucible can be installed as shown in FIGURE 4 in a combustion chamber with the pin in the same relative position to the induction coil each time a sample is tested. Tests with successive melts will result in better comparative accuracy, since the sample will tend to burn at the same rate because the induced current in the sample will be substantially the same. FIGURE 4 shows an induction heating coil 28 surrounding a high-temperature-resisting glass or fused quartz tube 30 which serves as the combustion charnber. The crucible 10 is supported on the upper end of a refractory sleeve 32 which is removably installed in the combustion chamber. An oxygen supply is directed over the sample by an inlet 34. The combustion gases are withdrawn from the combustion sample by an outlet 36.

The crucible 10 has a base 18 provided with a vfrustoconical projection 38 which is adapted to guide the base into nm engagement with the ceramic sleeve 32 to prevent lateral displacement of the crucible 10 with respect to sleeve 32 during installation of the crucible 10l in the combustion chamber 30.

I claim:

1. A crucible for a cornfbustion analyzer having side wall means around a sample space and lthe improvement comprising an inner oor dened by two flat faces sloping inwardly and downwardly and intersecting at an elongated linear apex.

2. A crucible in accordance with claim 1 wherein said Crucible is cylindrical and said side walls have concentric inner and outer cylindrical faces and in which said fiat faces intersect on a diameter of said inner cylindrical face.

References Cited UNITED STATES PATENTS Sweet 263-418 Moore 13-26 Mack 219-10.67 Wrou'gl'itron et al. 263-11 X Bennet 263-48 Rohn 263-48 10 JOHN J. CAMBY, Acting Primary Examiner. 

